Time Series Analysis of Onchocerciasis Data from Mexico: A Trend towards Elimination Edgar E. Lara-Ramı ´rez 1. , Mario A. Rodrı´guez-Pe ´ rez 1. , Miguel A. Pe ´rez-Rodrı´guez 1 , Monsuru A. Adeleke 2 , Marı ´a E. Orozco-Algarra 3 , Juan I. Arrendondo-Jime ´ nez 3 , Xianwu Guo 1 * 1 Centro de Biotecnologı ´a Geno ´ mica, Instituto Polite ´cnico Nacional, Reynosa, Tamaulipas, Me ´ xico, 2 Public Health Entomology and Parasitology Unit, Department of Biological Sciences, Osun State University, Osogbo, Osun, Nigeria, 3 Centro Nacional de Vigilancia Epidemiolo ´ gica y Control de Enfermedades, Secretaria de Salud, Me ´xico Distrito Federal, Me ´xico Abstract Background: In Latin America, there are 13 geographically isolated endemic foci distributed among Mexico, Guatemala, Colombia, Venezuela, Brazil and Ecuador. The communities of the three endemic foci found within Mexico have been receiving ivermectin treatment since 1989. In this study, we predicted the trend of occurrence of cases in Mexico by applying time series analysis to monthly onchocerciasis data reported by the Mexican Secretariat of Health between 1988 and 2011 using the software R. Results: A total of 15,584 cases were reported in Mexico from 1988 to 2011. The data of onchocerciasis cases are mainly from the main endemic foci of Chiapas and Oaxaca. The last case in Oaxaca was reported in 1998, but new cases were reported in the Chiapas foci up to 2011. Time series analysis performed for the foci in Mexico showed a decreasing trend of the disease over time. The best-fitted models with the smallest Akaike Information Criterion (AIC) were Auto-Regressive Integrated Moving Average (ARIMA) models, which were used to predict the tendency of onchocerciasis cases for two years ahead. According to the ARIMA models predictions, the cases in very low number (below 1) are expected for the disease between 2012 and 2013 in Chiapas, the last endemic region in Mexico. Conclusion: The endemic regions of Mexico evolved from high onchocerciasis-endemic states to the interruption of transmission due to the strategies followed by the MSH, based on treatment with ivermectin. The extremely low level of expected cases as predicted by ARIMA models for the next two years suggest that the onchocerciasis is being eliminated in Mexico. To our knowledge, it is the first study utilizing time series for predicting case dynamics of onchocerciasis, which could be used as a benchmark during monitoring and post-treatment surveillance. Citation: Lara-Ramı ´rez EE, Rodrı ´guez-Pe ´rez MA, Pe ´rez-Rodrı ´guez MA, Adeleke MA, Orozco-Algarra ME, et al. (2013) Time Series Analysis of Onchocerciasis Data from Mexico: A Trend towards Elimination. PLoS Negl Trop Dis 7(2): e2033. doi:10.1371/journal.pntd.0002033 Editor: Marı ´a-Gloria Basa ´n ˜ ez, Imperial College London, Faculty of Medicine, School of Public Health, United Kingdom Received May 25, 2012; Accepted December 12, 2012; Published February 14, 2013 Copyright: ß 2013 Lara-Ramı ´rez et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The authors have no support or funding to report. Competing Interests: The authors have declared that no competing interests exist. * E-mail: xguo@ipn.mx . These authors contributed equally to this work. Introduction Human onchocerciasis is caused by the filarial worm Onchocerca volvulus, which is transmitted by the bites of blackflies of Simulium species [1]. The symptomatology of onchocerciasis disease is characterized by clinical manifestations such as onchocerca skin diseases, onchocercomata, lymphadenopathy, and ocular lesions, including the irremediable terminal effect of blindness [2]. Onchocerciasis is the major cause of blindness and dermatitis in endemic areas, and it remains as an important public health problem in Africa. In Latin America, there are six countries (Brazil, Colombia, Ecuador, Venezuela, Guatemala, and Mexico) with scattered and small endemic onchocerciasis foci, where a population of 470, 222 individuals is currently estimated to be at risk [3]. The discovery of onchocerciasis in America was in 1915 by Rodolfo Robles in Guatemala; hence it was first named as Robles’s disease. In Mexico, the first cases of onchocerciasis were documented in 1923 in Chiapas, originated as a consequence of active seasonal migration of coffee workers from the endemic areas between Guatemala and Mexico. The regions in Chiapas and Oaxaca of Mexico are associated with the presence of abundant vector populations [4]. The focus of Oaxaca and Northern Chiapas represented the expansion of onchocerciasis from Southern Mexico or Guatemala [5]. The onchocerciasis control program in Mexico was first established in 1930 and has worked continuously up to date. During 1930–1946, a sporadic larval vector control campaign using Creolin was carried out to eliminate vector populations from breeding sites together with nodulectomy (removal of nodules) campaigns [6]. The administration of diethylcarbamazine (DEC) began in 1947, followed by a sporadic application of DDT to eliminate the vector populations in 1952. In 1990, DEC was supplanted by ivermectin (Mectizan; Merck & Co., Inc., White- house Station, NJ) [4]. In 1992, the Onchocerciasis Elimination Program for the Americas (OEPA) was launched [7], and has PLOS Neglected Tropical Diseases | www.plosntds.org 1 February 2013 | Volume 7 | Issue 2 | e2033